Electrolytic capacitor with open circuit mode mechanism

ABSTRACT

An electrolytic capacitor (K1-K3) with an open circuit mode mechanism, comprises: a metallic casing (32; 52; 62) for accommodating a capacitor element (31; 51; 61); an upper lid (33; 53; 63) which is mounted on a mouth of the metallic casing; a pair of metallic rivets (35; 54; 65) which are secured to the upper lid; a pair of external connection terminals (39; 55; 70) each of which is connected to one end portion of each of the metallic rivets; and a fixing member (40; 56; 71) which is molded by resin and is formed with a pair of through-holes (41; 57; 72) each for passing the other end portion of each of the metallic rivets therethrough such that the other end of each of the metallic rivets projecting out of the fixing member is connected, by metallic junction, to each of a pair of lead-out lead plates (42; 58; 73) drawn from the capacitor element. In case pressure in the metallic casing rises due to a malfunction of the electrolytic capacitor, the upper lid is deformed by this rise of the pressure, so that the metallic rivets are lifted in a direction away from the capacitor element upon this deformation of the upper lid and thus, the metallic junction between the other end of each of the metallic rivets and each of the lead-out lead plates is cut off, thereby resulting in break of an electric circuit of the electrolytic capacitor.

TECHNICAL FIELD

The present invention relates to an electrolytic capacitor with an opencircuit mode mechanism, in which at the time the electrolytic capacitormalfunctions, an upper lid is deformed due to rise of pressure in ametallic casing so as to break an electric circuit in the casing.

BACKGROUND ART

A conventional aluminum electrolytic capacitor has been arranged asshown in FIG. 8. Namely, in FIG. 8, a capacitor element 1 is impregnatedwith driving electrolyte and two lead-out lead plates 2a and 2b aredrawn from the capacitor element 1. A mouth sealing member 3 for sealinga mouth of a cylindrical metallic casing 9 made of, for example,aluminum and having a bottom is formed by laminating a rubber plate 3aand a resinous plate 3b integrally, while a-pair of metallic rivets 4amade of, for example, aluminum and a pair of metallic rivets 4b made of,for example, aluminum are pierced through the mouth sealing member 3. Anexternal connecting terminal 5a is connected to one end of one of therivets 4a and the lead-out lead plate 2a is connected to the other endof the one of the rivets 4a by crimping through metallic washers 6a and7a made of, for example, aluminum. Likewise, an external connectingterminal 5b is connected to one end of one of the rivets 4b and thelead-wire lead plate 2b is connected to the other end of the one of therivets 4b by crimping through metallic washers 6b and 7b made of, forexample, aluminum. The capacitor element 1 and the mouth sealing member3 provided integrally in this way are accommodated in the metalliccasing 9 containing fixing agent 8. The metallic casing 9 is subjectedto transverse drawing in the vicinity of the mouth. A distal end of themouth of the metallic casing 9 is subjected to curling so as to retainthe mouth sealing member 3. Meanwhile, a weak spot (not shown) formed bya thin wall portion is provided on the bottom of the metallic casing 9.

In case a voltage higher than its rated voltage is applied to theconventional aluminum electrolytic capacitor, temperature in themetallic casing 9 rises, so that organic solvent forming the drivingelectrolyte impregnated in the capacitor element 1 is vaporized andhydrogen gas is generated by electrochemical reaction. As a result,internal pressure of the metallic casing 9 accommodating the capacitorelement 1 rises. If the internal pressure of the metallic casing 9 risesexcessively, the weak portion provided on the bottom of the metalliccasing 9 is ruptured, so that the organic solvent gas flows out of themetallic casing 9 through the ruptured weak portion, thereby resultingin prevention of a tremendous explosion of the metallic casing 9.

However, in the above known aluminum electrolytic capacitor, since thedriving electrolyte gas spouts out of the metallic casing 9 in mistystate, such problems arise that this spouted misty driving electrolytegas soils interior of an electronic appliance incorporating the knownaluminum electrolytic capacitor and is mistaken for smoke due to a fire.

In order to solve these problems of the known aluminum electrolyticcapacitor, an electrolytic capacitor with an open circuit mode mechanismas shown in FIGS. 9A and 9B is proposed in, for example, JapaneseUtility Model Publication No. 6-39446 (1994). This prior artelectrolytic capacitor with the open circuit mode mechanism is arrangedas follows. Namely, in FIG. 9A, a capacitor element 12 is accommodatedin a metallic casing 11 and a metallic upper lid 14 is hermeticallymounted on an upper peripheral edge of a mouth of the metallic casing 11through an annular elastic packing 13. A pair of first rivets 15 arepierced through the metallic upper lid 14 and each of the first rivets15 is a composite rivet in which a metallic rivet 15b made of iron ormetal other than aluminum is press fitted into an opening of an aluminumhollow rivet 15a so as to be welded to the aluminum hollow rivet 15a.Each of the first rivets 15 not only is hermetically mounted on themetallic upper lid 14 but is electrically insulated from the metallicupper lid 14 by a silicone rubber piece 17 which is compressedly grippedbetween an insulating member 16 molded by resin and the aluminum hollowrivet 15a.

Meanwhile, an external terminal 18 is welded to an upper end of themetallic rivet 15b. An aluminum foil plate 19 having a weak portion iswelded to the aluminum hollow rivet 15a and is fixed, through analuminum washer 23, to a lead-out lead foil plate 22 from the capacitorelement 12 by a second rivet 21 mounted on a fixing plate 20 molded byresin so as to be connected to the lead-out lead foil plate 22.

In the prior art electrolytic capacitor with the open circuit modemechanism as shown in FIG. 9A, in case pressure in the metallic casing11 rises due to a malfunction in the prior art electrolytic capacitor asshown in FIG. 9B, the metallic upper lid 14 is deformed greatly to swellout upwardly upon rise of the pressure in the metallic casing 11.Therefore, in response to this upward deformation of the metallic upperlid 14, the first rivet 15 which not only is hermetically mounted on themetallic upper lid 14 but is electrically insulated from the metallicupper lid 14 by the compressed silicone rubber piece 17 is also deformedupwardly, so that the aluminum foil plate 19 welded to the aluminumhollow rivet 15a of the first rivet 15 is pulled upwardly and thus, iscut off at the weak portion. As a result, connection between thealuminum foil plate 19 and the lead-out lead foil plate 22 from thecapacitor element 22 is cut and thus, an electric circuit of the priorart electrolytic capacitor is broken.

However, in the prior art electrolytic capacitor with the open circuitmode mechanism as shown in FIGS. 9A and 9B, as many as six components,i.e., the metallic rivet 15b and the aluminum hollow rivet 15a of thefirst rivet 15, the aluminum foil plate 19, the second rivet 21, thealuminum washer 23 and the lead-out lead foil plate 22 are provided in aflow path of electric current from the external terminal 18 to thecapacitor element 12, structure of the prior art electrolytic capacitoris made complicated and the number of its assembly steps also increases.Meanwhile, the prior art electrolytic capacitor has such a disadvantagethat the number of connections of the six components reaches as many asfive, thereby resulting in poor reliability of connections of thecomponents.

Meanwhile, when the open circuit mode mechanism is actuated, themetallic upper lid 14 is deformed so as to swell out upwardly as shownin FIG. 9B, interval between a pair of the external terminals 18 isincreased. Therefore, in case the external terminals 18 are restrictedby holes of a printed circuit board or the like, such inconveniences areincurred that the open circuit mode mechanism malfunctions and theprinted circuit board is damaged by the external terminals 18 uponincrease of interval between the external terminals 18.

Furthermore, since the aluminum foil plate 19 having the weak portion ofsmall cross-sectional area for reducing its mechanical strength isprovided in the course of the electric circuit for passing large ACtherethrough from the external terminal 18 to the capacitor element 12,electric resistance rises at the weak portion and thus, the weak portionis heated by the AC. As a result, the prior art electrolytic capacitorhas such a disadvantage that ripple current (AC) capacity, one of basicfeatures of the electrolytic capacitor is sacrificed.

DISCLOSURE OF INVENTION

Accordingly, the present invention has for its object to provide, with aview to eliminating the above mentioned disadvantages inherent in priorart, an electrolytic capacitor with an open circuit mode mechanismfunctioning properly, in which the number of connections amongcomponents in a flow path of electric current from an externalconnection terminal to a capacitor element is reduced greatly and a weakspot having a reduced cross-sectional area is eliminated from the flowpath of electric current.

This object and features of the present invention will become clear fromthe following description taken in conjunction with the preferredembodiments thereof with reference to the accompanying drawingsthroughout which like parts are designated by like reference numerals.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal sectional view of an electrolytic capacitorwith an open circuit mode mechanism, according to a first embodiment ofthe present invention.

FIG. 2 is a longitudinal sectional view of an electrolytic capacitorwith an open circuit mode mechanism, according to a second embodiment ofthe present invention.

FIGS. 3A and 3B are longitudinal sectional views of an electrolyticcapacitor with an open circuit mode mechanism, according to a thirdembodiment of the present invention.

FIG. 4 is a partially broken fragmentary perspective view of theelectrolytic capacitor of FIG. 3A.

FIG. 5 is a longitudinal sectional view of an electrolytic capacitorwith an open circuit mode mechanism, according to a fourth embodiment ofthe present invention.

FIG. 6 is a longitudinal sectional view of an electrolytic capacitorwith an open circuit mode mechanism, according to a fifth embodiment ofthe present invention.

FIG. 7 is a longitudinal sectional view of an electrolytic capacitorwith an open circuit mode mechanism, according to a sixth embodiment ofthe present invention.

FIG. 8 is a longitudinal sectional view of a prior art electrolyticcapacitor.

FIGS. 9A and 9B are longitudinal sectional views of another prior artelectrolytic capacitor with an open circuit mode mechanism.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention aredescribed with reference to the attached drawings.

First Embodiment

FIG. 1 shows an electrolytic capacitor K1 with an open circuit modemechanism, according to a first embodiment of the present invention. InFIG. 1, an anode foil and a cathode foil are wound so as to interpose aseparator therebetween in a capacitor element 31. After the capacitorelement 31 has been impregnated with driving electrolyte, the capacitorelement 31 is accommodated in a cylindrical metallic casing 32 made of,for example, aluminum and having a bottom. A metallic upper lid 33 forclosing a mouth of the metallic casing 32 is mounted on the mouth of themetallic casing 32 through an annular packing 34 made of elastic rubber.An insulating member 36 molded by phenol resin is attached to one endportion of each of a pair of metallic rivets 35 made of, for example,aluminum so as to partially penetrate into each of a pair ofthrough-holes 37 formed on the upper lid 33.

In order to fix the metallic rivets 35 to the upper lid 33, each of themetallic rivets 35 is pierced through the upper lid 33 via theinsulating member 36. Then, the other end portion of each of themetallic rivets 35 is pierced through a resinous molded member formedintegrally by elastic rubber or a resinous laminated board 38 of rubberbonding. Subsequently, by crimping the other end portion of each of themetallic rivets 35, the metallic rivets 35 are hermetically fixed to theupper lid 33 so as to be electrically insulated from the upper lid 33.An external connection terminal 39 is connected to the one end portionof each of the metallic rivets 35. A fixing member 40 molded by resin isformed with a pair of through-holes 41 each for passing the other endportion of each of the metallic rivets 35 therethrough. The other end ofeach of the metallic rivets 35 passing through the through-holes 41 ofthe fixing member 40 and projecting out of the fixing member 40 in thedirection opposite to the upper lid 33 and each of a pair of lead-outlead plates 42 drawn from the capacitor element 31 are subjected tometallic junction by ultrasonic welding so as to be electricallyconnected to each other. The through-hole 41 of the fixing member 40 isset at a diameter of such a small dimensional allowance that the otherend portion of each of the metallic rivets 35 can be barely insertedthereinto.

A projection 40a is integrally formed at a substantially central portionof the fixing member 40 and is inserted into a winding core cavity 31aof the capacitor element 31 so as to secure the capacitor element 31 tothe fixing member 40. A plurality of communication holes 43 for formingcommunication between the capacitor element 31 and the upper lid 33 areformed on the fixing member 40. The capacitor element 31, the fixingmember 40, the metallic rivets 35, the upper lid 33, etc. providedintegrally as described above are accommodated in the metallic casing 32which contains fixing agent 44 and is subjected to transverse drawing inthe vicinity of the mouth so as to have a transverse drawing portion32a. A distal end of the mouth of the metallic casing 32 is subjected tocurling so as to retain the fixing member 40, the upper lid 33, etc.

In the electrolytic capacitor K1 with the open circuit mode mechanism,according to the first embodiment of the present invention as shown inFIG. 1, in case pressure in the metallic casing 32 rises due to amalfunction of the electrolytic capacitor K1, the pressure is applied tothe upper lid 33 through the communication holes 43 of the fixing member40 so as to deform the upper lid 33 such that the upper lid 33 swellsout upwardly. In response to this deformation of the upper lid 33, themetallic rivets 35 secured to the upper lid 33 are also pulled upwardlyby the upper lid 33, so that the connections of ultrasonic weldingbetween the lead-out lead plates 42 from the capacitor element 31disposed below the fixing member 40 and the metallic rivets 35 arepulled upwardly by the metallic rivets 35. In this case, thethrough-hole 41 for inserting the metallic rivet 35 therethrough in thefixing member 40 is set at an area smaller than that of the lead-outlead plate 42 at the connection between the lead-out lead plate 42 andthe metallic rivet 35. Therefore, even if the lead-out lead plate 42would penetrate into the through-hole 41 in response to upwarddeformation of the metallic rivet 35, the lead-out lead plate 42 is notcapable of penetrating into the through-hole 41. As a result, theconnection of ultrasonic welding between each of the metallic rivets 35and each of the lead-out lead plates 42 is cut off by an edge of each ofthe through-holes 41 and thus, an electric circuit of the electrolyticcapacitor K1 is broken.

Accordingly, the electrolytic capacitor K1 eliminates such drawbacks ofan prior art electrolytic capacitor including a metallic casing having aweak spot formed by a thin wall portion of the bottom that misty drivingelectrolyte spouted out of the metallic casing soils interior of anelectronic appliance incorporating the prior art electrolytic capacitorand is mistaken for smoke due to a fire.

Second Embodiment

FIG. 2 shows an electrolytic capacitor K2 with an open circuit modemechanism, according to a second embodiment of the present invention. InFIG. 2, an anode foil and a cathode foil are wound so as to interpose aseparator therebetween in a capacitor element 51. After the capacitorelement 51 has been impregnated with driving electrolyte, the capacitorelement 51 is accommodated in a cylindrical metallic casing 52 made of,for example, aluminum and having a bottom. A mouth sealing member 53 forclosing a mouth of the metallic casing 52 and is formed by integrallylaminating a rubber plate 53b on a baking plate 53a. This mouth sealingmember 53 performs three functions of the metallic upper lid 33, theinsulating member 36 molded by phenol resin and the resinous laminatedboard 38 of the electrolytic capacitor K1 of FIG. 1. By employing themouth sealing member 53, the electrolytic capacitor K2 is madestructurally simpler than the electrolytic capacitor K1.

A pair of metallic rivets 54 made of, for example, aluminum are piercedthrough the mouth sealing member 53. By crimping portions of each of themetallic rivets 54 projecting from the mouth sealing member 53 upwardlyand downwardly, respectively, each of the metallic rivets 54 is securedto the mouth sealing member 53. An external connection terminal 55 isconnected to one end portion of each of the metallic rivets 54. A fixingmember 56 molded by resin is formed with a pair of through-holes 57 eachfor passing the other end portion of each of the metallic rivets 54therethrough. The other end of each of the metallic rivets 54 passingthrough the through-holes 57 of the fixing member 56 and projecting outof the fixing member 56 in the direction opposite to the mouth sealingmember 53 and each of lead-out lead plates 58 drawn from the capacitorelement 51 are subjected to metallic junction by ultrasonic welding soas to be electrically connected to each other. The through-hole 57 ofthe fixing member 56 is set at a diameter of such a small dimensionalallowance that the other end portion of each of the metallic rivets 54can be barely inserted thereinto. A plurality of communication holes 59for forming communication between the capacitor element 51 and the mouthsealing member 53 are formed on the fixing member 56.

The capacitor element 51, the fixing member 56, the metallic rivets 54and the mouth sealing member 53 provided integrally as described aboveare accommodated in the metallic casing 52 which contains fixing agent60 and is subjected to transverse drawing in the vicinity of the mouthso as to have a transverse drawing portion 52a. A distal end of themouth of the metallic casing 52 is subjected to curling so as to retainthe fixing member 56 and the mouth sealing member 53.

In the electrolytic capacitor K2 with the open circuit mode mechanism,according-to the second embodiment of the present invention as shown inFIG. 2, in case pressure in the metallic casing 52 rises due to amalfunction of the electrolytic capacitor K2, the pressure is applied tothe mouth sealing member 53 through the communication holes 59 of thefixing member 56 so as to deform the mouth sealing member 53 such thatthe mouth sealing member 53 swells out upwardly. In response to thisdeformation of the mouth sealing member 53, the metallic rivets 54secured to the mouth sealing member 53 are also pulled upwardly by themouth sealing member 53, so that the connections of ultrasonic weldingbetween the lead-out lead plate 58 from the capacitor element 51disposed below the fixing member 56 and the metallic rivets 54 arepulled upwardly by the metallic rivets 54. In this case, thethrough-hole 57 for inserting the metallic rivet 54 therethrough in thefixing member 56 is set at an area smaller than that of the lead-outlead plate 58 at the connection between the lead-out lead plate 58 andthe metallic rivet 54. Therefore, even if the lead-out lead plate 58would penetrate into the through-hole 57 in response to upwarddeformation of the metallic rivet 54, the lead-out lead plate 58 is notcapable of penetrating into the through-hole 57. As a result, theconnection of ultrasonic welding between each of the metallic rivets 54and each of the lead-out lead plates 58 is cut off by an edge of each ofthe through-holes 57 and thus, an electric circuit of the electrolyticcapacitor K2 is broken.

Accordingly, the electrolytic capacitor K2 eliminates such drawbacks ofthe prior art electrolytic capacitor including the metallic casinghaving the weak spot formed by the thin wall portion of the bottom thatmisty driving electrolyte spouted out of the metallic casing soilsinterior of the electronic appliance incorporating the prior artelectrolytic capacitor and is mistaken for smoke due to a fire.

Third Embodiment

FIGS. 3A and 3B show an electrolytic capacitor K3 with an open circuitmode mechanism, according to a third embodiment of the presentinvention. In FIG. 3A, an anode foil and a cathode foil are wound so asto interpose a separator therebetween in a capacitor element 61. Afterthe capacitor element 61 has been impregnated with driving electrolyte,the capacitor element 61 is accommodated in a cylindrical metalliccasing 62 made of, for example, aluminum and having a bottom. A metallicupper lid 63 for closing a mouth of the metallic casing 62 is mounted onthe mouth of the metallic casing 62 through an annular packing 64 madeof elastic rubber. An insulating member 66 molded by phenol resin isattached to one end portion of each of a pair of metallic rivets 65 madeof, for example, aluminum. An insulating ring 67 is press fitted intoeach of a pair of through-holes 68 formed on the upper lid 63.

In order to fix the metallic rivets 65 to the upper lid 63, each of themetallic rivets 65 is pierced through the insulating ring 67 via theinsulating member 66. Then, the other end portion of each of themetallic rivets 65 is pierced through a resinous laminated board 69 ofrubber bonding. Subsequently, by crimping the other end portion of eachof the metallic rivets 65, the metallic rivets 65 are hermetically fixedto the upper lid 63 so as to be electrically insulated from the upperlid 63. An external connection terminal 70 is connected to the one endportion of each of the metallic rivets 65. A fixing member 71 molded byresin is formed with a pair of through-holes 72 each for passing theother end portion of each of the metallic rivets 65 therethrough. Theother end of each of the metallic rivets 65 passing through thethrough-holes 72 of the fixing member 71 and projecting out of fixingmember 71 in the direction opposite to the upper lid 63 and each of apair of lead-out lead plates 73 drawn from the capacitor element 61 aresubjected to metallic junction by ultrasonic welding so as to beelectrically connected to each other. The through-hole 72 of the fixingmember 71 is set as a diameter of such a small dimensional allowancethat the other end portion of each of the metallic rivets 65 can bebarely inserted thereinto.

A projection 71a is integrally formed a substantially central portion ofthe fixing member 71 and is inserted into a winding core cavity 61a ofthe capacitor element 61 so as to secure the capacitor element 61 to thefixing member 71. A communication hole 74 for forming communicationbetween the capacitor element 61 and the upper lid 63 is formed on thefixing member 71. As shown in FIG. 4, four openings 75 for inserting ajig 76 thereinto are formed on the fixing member 71 so as to correspondto the two metallic rivets 65. By inserting forks 76a and 76b of the jig76 through the openings 75, each of the forks 76a and 76b is arranged togrip, from outside, the other end portion of each of the metallic rivets65 passing through the through-holes 72 of the fixing member 71.

The capacitor element 61, the fixing member 71, the metallic rivets 65,the upper lid 63, etc. provided integrally as described above areaccommodated in the metallic casing 62 which contains fixing agent 77and is subjected to transverse drawing in the vicinity of the mouth soas to have a transverse drawing portion 62a. A distal end of the mouthof the metallic casing 62 is subjected to curling so as to retain thefixing member 71, the upper lid 63, etc.

FIG. 3B shows a state in which the open circuit mode mechanism of theelectrolytic capacitor K3 of FIG. 3A is actuated. Namely, in casepressure in the metallic casing 62 rises due to a malfunction of theelectrolytic capacitor K3, the pressure is applied to the upper lid 63through the communication hole 74 of the fixing member 71 so as todeform the upper lid 63 such that the upper lid 63 swells out upwardly.However, since a central portion of the upper lid 63 is retained by theinsulating member 66 and the resinous laminated board 69, only an outerperipheral portion of the upper lid 63, which is not retained by theinsulating member 66 and the resinous laminated board 69, is deformedupwardly. In response to this upward deformation of the outer peripheralportion of the upper lid 63, the metallic rivets 65 secured to the upperlid 63 are also pulled upwardly by the upper lid 63, so that theconnections of ultrasonic welding between the lead-out lead plates 73from the capacitor element 61 disposed below the fixing member 71 andthe metallic rivets 65 are also pulled upwardly by the metallic rivets65. In this case, the through-hole 72 for inserting the metallic rivet65 therethrough in the fixing member 71 is set at an area smaller thanthat of lead-out lead plate 73 at the connection between the lead-outlead plate 73 and the metallic rivet 65. Therefore, even if the lead-outlead plate 73 would penetrate into the through-hole 72 in response toupward movement of the metallic rivet 65, the lead-out lead plate 73 isnot capable of penetrating into the through-hole 72. As a result, theconnection of ultrasonic welding between each of the metallic rivets 65and each of the lead-out lead plates 73 is cut off by an edge of each ofthe through-holes 72 and thus, an electric circuit of the electrolyticcapacitor K3 is broken.

Accordingly, the electrolytic capacitor K3 eliminates such drawbacks ofthe prior art electrolytic capacitor including the metallic casinghaving the weak spot formed by the thin wall portion of the bottom thatmisty driving electrolyte spouted out of the metallic casing soilsinterior of the electronic appliance incorporating the prior artelectrolytic capacitor and is mistaken for smoke due to a fire.

Meanwhile, since the central portion of the upper lid 63, which isretained by the insulating member 66 and the resinous laminated board69, is not deformed, interval between the external connection terminals70 does not change. Thus, not to mention, in a lug terminal type inwhich the external connection terminals 70 are not retained by a printedcircuit board or the like and also in another type in which the externalconnection terminals 70 are retained by a printed circuit board or thelike, the open circuit mode mechanism of the electrolytic capacitor K3functions properly. In addition, such a problem is also eliminated thatthe printed circuit board is damaged by increase of interval of theexternal connection terminals 70.

Furthermore, in the electrolytic capacitor K3, the openings 75 forinserting therethrough the jig 76 for gripping, from outside, the otherend portion of each of the metallic rivets 65 pierced through thethrough-holes 72 of the fixing member 71 are formed on the fixing member71. Therefore, in case the other end of each of the metallic rivets 65passing through the through-holes 72 of the fixing member 71 andprojecting out of the fixing member 71 in the direction opposite to theupper lid 63 and each of the lead-out lead plates 73 from the capacitorelement 61 are subjected to metallic junction by ultrasonic welding soas to be electrically connected to each other, this metallic junctioncan be performed easily and positively.

Namely, in case the other end of each of the metallic rivets 65 and eachof the lead-out lead plates 73 from the capacitor element 61 aresubjected to metallic junction by ultrasonic welding, it is importantfor securing reliability and strength of the junction to hold and securea portion of each of the metallic rivets 65 adjacent to the junctionlocation. If each of the metallic rivets 65 passing through thethrough-holes 72 of the fixing member 71 and projecting out of thefixing member 71 in the direction opposite to the upper lid 63 is heldand secured at one side of each of the metallic rivets 65 adjacent tothe capacitor element 61 and the distal end of each of the metallicrivets 65 and each of the lead-out lead plates 73 are subjected tometallic junction, a projecting distance of each of the metallic rivets65 from the lower face of the fixing member 71 to the metallic junctiondistal end of each of the metallic rivets 65 should be of such a lengthas to hold and secure the metallic rivets 65 with a jig and thus, wouldbecome rather long. If the projecting distance of each of the metallicrivets 65 becomes long as described above, the following undesirablephenomenon may happen. Namely, when the upper lid 63 is deformedupwardly in response to rise of pressure in the metallic casing 62 dueto a malfunction of the electrolytic capacitor and the metallic rivets65 are pulled upwardly by the upper lid 63 and the connection ofultrasonic welding between each of the metallic rivets 65 and each ofthe lead-out lead plates 73 is cut off by an edge of each of thethrough-holes 72 for passing the metallic rivets 65 therethrough in thefixing member 71, travel distance of each of the metallic rivets 65 willbecome long, thereby resulting in deterioration of reliability andresponse property of the electrolytic capacitor.

However, in the electrolytic capacitor K3, the openings 75 for insertingthereinto the jig 76 for gripping, from outside, the other end of eachof the metallic rivets 65 passing through the through-holes 72 of thefixing member 71 are formed on the fixing member 71. Therefore, in casethe other end of each of the metallic rivets 65 passing through thethrough-holes 72 of the fixing member 71 and projecting out of thefixing member 71 in the direction opposite to the upper lid 63 and eachof the lead-out lead plates 73 from the capacitor element 61 aresubjected to metallic junction by ultrasonic welding, the forks 76a and76b of the jig 76 are inserted through the openings 75 so as to grip,from outside, the other end portion of each of the metallic rivets 65passing through the through-holes 72 of the fixing member 71. As aresult, metallic junction between the other end of each of the metallicrivets 65 and each of the lead-out lead plates 73 from the capacitorelement 61 can be performed easily and positively. Furthermore, theprojecting distance of each of the metallic rivets 65 from the fixingmember 71 can be shortened by forming the openings 75 on the fixingmember 71. Consequently, in case the connection of ultrasonic weldingbetween each of the metallic rivets 65 and each of the lead-out leadplates 73 is cut off by a malfunction of the electrolytic capacitor K3,reliability and response property of the electrolytic capacitor K3 canbe upgraded.

Fourth Embodiment

FIG. 5 shows an electrolytic capacitor K4 with an open circuit modemechanism, according to a fourth embodiment of the present invention. Ananode foil and a cathode foil are wound so as to interpose a separatortherebetween in a capacitor element 81. After the capacitor element 81has been impregnated with driving electrolyte, the capacitor element 81is accommodated in a cylindrical metallic casing 82 made of, forexample, aluminum and having a bottom. A metallic upper lid 83 forclosing a mouth of the metallic casing 82 is mounted on the mouth of themetallic casing 82 through an annular packing 84 made of elastic rubber.A terminal fixing member 85 made of resin is attached to the upper lid83. A pair of metallic rivets 86 made of, for example, aluminum areintegrally held by the terminal fixing member 85 at the time of moldingof the terminal fixing member 85. An external connection terminal 87 isconnected to one end portion of each of the metallic rivets 86. A fixingmember 88 molded by resin is formed with a pair of through-holes 89 eachfor passing the other end portion of each of the metallic rivets 86therethrough. The other end of each of the metallic rivets 86 passingthrough the through-holes 89 of the fixing member 88 and projecting outof the fixing member 88 in the direction opposite to the upper lid 83and each of a pair of lead-out lead plates 90 drawn from the capacitorelement 81 are subjected to metallic junction by ultrasonic welding soas to be electrically connected to each other. The through-hole 89 ofthe fixing member 88 is set at a diameter of such a small dimensionalallowance that the other end portion of each of the metallic rivets 86can be barely inserted thereinto. A plurality of communication holes 91for forming communication between the capacitor element 81 and the upperlid 83 are formed on the fixing member 88.

The capacitor element 81, the fixing member 88, the upper lid 83, etc.provided integrally as described above are accommodated in the metalliccasing 82 which contains fixing agent 92 and is subjected to transversedrawing in the vicinity of the mouth so as to have a transverse drawingportion 82a. A distal end of the mouth of the metallic casing 82 issubjected to curling so as to retain the fixing member 88, the upper lid83, etc.

In the electrolytic capacitor K4 with the open circuit mode mechanism,according to the fourth embodiment of the present invention as shown inFIG. 5, in case pressure in the metallic casing 82 rises due to amalfunction of the electrolytic capacitor K4, the pressure is applied tothe upper lid 83 through the communication holes 91 of the fixing member88 so as to deform the upper lid 83 such that the upper lid 83 swellsout upwardly. In response to this deformation of the upper lid 83, themetallic rivets 86 are also pulled upwardly by the upper lid 83, so thatthe connections of ultrasonic welding between the lead-out lead plates90 from the capacitor element 81 disposed below the fixing member 88 andthe metallic rivets 86 are also pulled upwardly by the metallic rivets86. In this case, the through-hole 89 for inserting the metallic rivet86 therethrough is set at an area smaller than that of the lead-out leadplate 90 at the connection between lead-out lead plate 90 and themetallic rivet 86. Therefore, even if the lead-out lead plate 90 wouldpenetrate into the through-hole 89 in response to upward movement of themetallic rivet 86, the lead-out lead plate 90 is not capable ofpenetrating into the through-hole 89. As a result, the connection ofultrasonic welding between each of the metallic rivets 86 and each ofthe lead-out lead plates 90 is cut off by an edge of each of thethrough-holes 89 and thus, an electric circuit of the electrolyticcapacitor K4 is broken.

Accordingly, the electrolytic capacitor K4 eliminates such disadvantagesof the prior art electrolytic capacitor including the metallic casinghaving the weak spot formed by the thin wall portion of the bottom thatmisty driving electrolyte spouted out of the metallic casing soilsinterior of the electronic appliance incorporating the prior artelectrolytic capacitor and is mistaken for smoke due to a fire.

Meanwhile, in the electrolytic capacitor K4, since the metallic rivets86 each having the external connection terminal 87 connected to its oneend portion are integrally held by the terminal fixing member 85 at thetime of molding of the terminal fixing member 85 attached to the upperlid 83, interval between the external connection terminals 87 is fixed.Therefore, the electrolytic capacitor K4 can be quite usefully appliedto an electrolytic capacitor of a type in which a pair of the externalconnection terminals are inserted into holes of a printed circuit boardof an electronic appliance.

Namely, in the electrolytic capacitor K1 of FIG. 1, the insulatingmember 36 molded by phenol resin is mounted on one end portion of eachof the metallic rivets 35 so as to partially penetrate into thethrough-hole 37 of the upper lid 33 such that the external connectionterminal 39 is connected to the one end portion of each of the metallicrivets 35. Therefore, in the electrolytic capacitor K1, in case pressurein the metallic casing 32 rises due to a malfunction of the electrolyticcapacitor K1 and the upper lid 33 is deformed upwardly in response tothis rise of the pressure, interval between the external connectionterminals 39 connected to the one end portion of each of the metallicrivets 35 will be increased. If the interval between the externalconnection terminals 39 inserted into holes of a printed circuit boardof an electronic appliance is increased, the metallic rivets 35 are notpulled upwardly by the upper lid 33 in response to upward deformation ofthe upper lid 33. As a result, there are such risks that the connectionof ultrasonic welding between each of the lead-out lead plates 42 fromthe capacitor element 31 and each of the metallic rivets 35 is not cutoff properly and fractures or cracks are produced in the vicinity of theholes of the printed circuit board of the electronic appliance.

On the other hand, in the electrolytic capacitor K4 of FIG. 5, themetallic rivets 86 each having the external connection terminal 87connected to its one end portion are integrally held by the terminalfixing member 85 at the time of molding of the terminal fixing member 85attached to the upper lid 83. Therefore, in case pressure in themetallic casing 82 rises due to a malfunction of the electrolyticcapacitor K4 and the upper lid 83 is deformed upwardly in response tothis rise of the pressure, the terminal fixing member 85 attached to theupper lid 83 is also deformed upwardly integrally with the upper lid 83.As a result, such a phenomenon is eliminated that interval between theexternal connection terminals 87 at the metallic rivets 86 integrallyheld by the terminal fixing member 85 is increased in response to upwarddeformation of the upper lid 83. Therefore, in the case where theexternal connection terminals 87 are inserted into the holes of theprinted circuit board of the electronic appliance, neither fractures norcracks are produced in the vicinity of the holes of the printed circuitboard.

Fifth Embodiment

FIG. 6 shows an electrolytic capacitor K5 with an open circuit modemechanism, according to a fifth embodiment of the present invention. Ananode foil and a cathode foil are wound so as to interpose a separatortherebetween in a capacitor element 101. After the capacitor element 101has been impregnated with driving electrolyte, the capacitor element 101is accommodated in a cylindrical metallic casing 102 made of, forexample, aluminum and having a bottom. A metallic upper lid 103 forclosing a mouth of the metallic casing 102 is mounted on the mouth ofthe metallic casing 102 through an annular packing 104 made of elasticrubber. A terminal fixing member 105 made of resin is attached to theupper lid 103. A pair of metallic rivets 106 made of, for example,aluminum are integrally held by the terminal fixing member 105 at thetime of molding of the terminal fixing member 105. An externalconnection terminal 107 is connected to one end portion of each of themetallic rivets 106. A fixing member 108 molded by resin is formed witha pair of through-holes 109 each for passing the other end portion ofeach of the metallic rivets 106 therethrough. The other end of each ofthe metallic rivets 106 passing through the through-holes 109 of thefixing member 108 and projecting out of the fixing member 108 in thedirection opposite to the upper lid 103 and each of a pair of lead-outlead plates 110 drawn from the capacitor element 101 are subjected tometallic junction by ultrasonic welding so as to be electricallyconnected to each other. The through-hole 109 of the fixing member 108is set at a diameter of such a small dimensional allowance that theother end portion of each of the metallic rivets 106 can be barelyinserted thereinto. A plurality of communication holes 111 for formingcommunication between the capacitor element 101 and the upper lid 103are formed on the fixing member 108. Meanwhile, an annular weak portion105a formed by a thin wall portion of low mechanical strength isprovided at a portion of a peripheral edge of the terminal fixing member105.

The capacitor element 101, the fixing member 108, the upper lid 103,etc. provided integrally as described above are accommodated in themetallic casing 102 which contains fixing agent 112 and is subjected totransverse drawing in the vicinity of the mouth so as to have atransverse drawing portion 102a. A distal end of the mouth of themetallic casing 102 is subjected to curling so as to retain the fixingmember 108, the upper lid 103, etc.

In the electrolytic capacitor K5 with the open circuit mode mechanism,according to the fifth embodiment of the present invention as shown inFIG. 6, in case pressure in the metallic casing 102 rises due to amalfunction of the electrolytic capacitor K5, the pressure is applied tothe upper lid 103 through the communication holes 111 of the fixingmember 108 so as to deform the upper lid 103 such that the upper lid 103swells out upwardly. In response to this deformation of the upper lid103, the metallic rivets 106 are also pulled upwardly by the upper lid103, so that the connections of ultrasonic welding between the lead-outlead plates 110 from the capacitor element 101 disposed below the fixingmember 108 and the metallic rivets 106 are also pulled upwardly by themetallic rivets 106. In this case, the through-hole 109 for insertingthe metallic rivet 106 therethrough is set at an area smaller than thatof the lead-out lead plate 110 at the connection between lead-out leadplate 110 and the metallic rivet 106. Therefore, even if the lead-outlead plate 110 would penetrate into the through-hole 109 in response toupward movement of the metallic rivet 106, the lead-out lead plate 110is not capable of penetrating into the through-hole 109. As a result,the connection of ultrasonic welding between each of the metallic rivets106 and each of the lead-out lead plates 110 is cut off by an edge ofeach of the through-holes 109 and thus, an electric circuit of theelectrolytic capacitor K5 is broken.

Accordingly, the electrolytic capacitor K5 eliminates such disadvantagesof the prior art electrolytic capacitor including the metallic casinghaving the weak spot formed by the thin wall portion of the bottom thatmisty driving electrolyte spouted out of the metallic casing soilsinterior of the electronic appliance incorporating the prior artelectrolytic capacitor and is mistaken for smoke due to a fire.

In the electrolytic capacitor K5, operating efficiency of the opencircuit mode mechanism is improved greatly. Namely, the annular weakportion 105a formed by the thin wall thickness portion of low mechanicalstrength is provided at the portion of the peripheral edge of theterminal fixing member 105. Therefore, in case pressure in the metalliccasing 102 rises due to a malfunction of the electrolytic capacitor K5,the upper lid 103 and the terminal fixing member 105 are integrallydeformed upwardly in response to this rise of the pressure, so that theweak portion 105a of low mechanical strength in the terminal fixingmember 105 is initially fractured at a predetermined pressure and thus,the terminal fixing member 105 is displaced suddenly. As a result, theconnection between each of the lead-out lead plates 110 and each of themetallic rivets 106 is also pulled upwardly suddenly in response to thisdisplacement of the terminal fixing member 105 and thus, is cut off byan edge of each of the through-holes 109 of the fixing member 108,thereby resulting in remarkable improvement of operating efficiency ofthe open circuit mode mechanism of the electrolytic capacitor K5.

Sixth Embodiment

FIG. 7 shows an electrolytic capacitor K6 with an open circuit modemechanism, according to a sixth embodiment of the present invention. Ananode foil and a cathode foil are wound so as to interpose a separatortherebetween in a capacitor element 121. After the capacitor element 121has been impregnated with driving electrolyte, the capacitor element 121is accommodated in a cylindrical metallic casing 122 made of, forexample, aluminum and having a bottom. A metallic upper lid 123 forclosing a mouth of the metallic casing 122 is mounted on the mouth ofthe metallic casing 122 through an annular packing 124 made of elasticrubber. A terminal fixing member 125 made of resin is attached to theupper lid 123. A pair of metallic rivets 126 made of, for example,aluminum are integrally held by the terminal fixing member 125 at thetime of molding of the terminal fixing member 125. An externalconnection terminal 127 is connected to one end portion of each of themetallic rivets 126. A fixing member 128 molded by resin is formed witha pair of through-holes 129 each for passing the other end portion ofeach of the metallic rivets 126 therethrough. The other end of each ofthe metallic rivets 126 passing through the through-holes 129 of thefixing member 128 and projecting out of the fixing member 128 in thedirection opposite to the upper lid 123 and each of a pair of lead-outlead plates 130 drawn from the capacitor element 121 are subjected tometallic junction by ultrasonic welding so as to be electricallyconnected to each other. The through-hole 129 of the fixing member 128is set at a diameter of such a small dimensional allowance that theother end portion of each of the metallic rivets 126 can be barelyinserted thereinto. A plurality of communication holes 131 for formingcommunication between the capacitor element 121 and the upper lid 123are formed on the fixing member 128. Meanwhile, a longitudinallyextending cylindrical plastic elongation portion 123a is integrallyformed at a peripheral edge of the upper lid 123. This plasticelongation portion 123a is elastically deformed at a pressure less thana predetermined value but is plastically deformed at a pressure not lessthan the predetermined value so as to suddenly deform the upper lid 123upwardly.

The capacitor element 121, the fixing member 128, the upper lid 123,etc. provided integrally as described above are accommodated in themetallic casing 122 which contains fixing agent 132 and is subjected totransverse drawing in the vicinity of the mouth so as to have atransverse drawing portion 122a. A distal end of the mouth of themetallic casing 122 is subjected to curling so as to retain the fixingmember 128, the upper lid 123, etc.

In the electrolytic capacitor K6 with the open circuit mode mechanism,according to the sixth embodiment of the present invention as shown inFIG. 7, in case pressure in the metallic casing 122 rises due to amalfunction of the electrolytic capacitor K6, the pressure is applied tothe terminal fixing member 125 through the communication holes 131 ofthe fixing member 128 so as to deform the upper lid 123 upwardly by wayof the terminal fixing member 125. In this case, since thelongitudinally extending cylindrical plastic elongation portion 123a isintegrally formed at the peripheral edge of the upper lid 123, the upperlid 123 is arranged to be elastically deformed at a pressure less thanthe predetermined value but be plastically deformed at a pressure notless than the predetermined value. As a result, since the upper lid 123is suddenly deformed upwardly, the connection between each of thelead-out lead plates 130 and each of the metallic rivets 126 is alsosuddenly pulled upwardly and is cut off by an edge of each of thethrough-holes 129 of the fixing member 128, so that an electric circuitof the electrolytic capacitor K6 is broken.

Accordingly, the electrolytic capacitor K6 eliminates such disadvantagesof the prior art electrolytic capacitor including the metallic casinghaving the weak spot formed by the thin wall portion of the bottom thatmisty driving electrolyte spouted out of the metallic casing soilsinterior of the electronic appliance incorporating the prior artelectrolytic capacitor and is mistaken for smoke due to a fire. Inaddition, operating efficiency of the open circuit mode mechanism of theelectrolytic capacitor K6 is improved remarkably.

Meanwhile, in the above mentioned embodiments of the present invention,metallic junction between the other end of each of the metallic rivetsand each of the lead-out lead plates from the capacitor element isperformed by ultrasonic welding but is not limited to ultrasonicwelding. For example, ultrasonic welding may be replaced by one of laserwelding, cold pressure welding and crimping.

Although the present invention has been fully described in connectionwith the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom.

Industrial Applicability

In the above mentioned electrolytic capacitor with the open circuit modemechanism, according to the present invention, the upper lid is mounted,through the packing, on the mouth of the cylindrical metallic casinghaving the bottom and a pair of the metallic rivets are fixed to theupper lid so as to be passed through the upper lid. Furthermore, each ofa pair of the external connection terminals is connected to one endportion of each of the metallic rivets, while the other end portion ofeach of the metallic rivets is passed through each of the through-holesformed on the fixing member molded by resin. In addition, the other endof each of the metallic rivets passing through each of the through-holesof the fixing member and projecting out of the fixing member in thedirection opposite to the upper lid and each of a pair of the lead-outlead plates from the capacitor element accommodated in the metalliccasing are connected to each other by metallic junction.

In case pressure in the metallic casing rises due to a malfunction ofthe electrolytic capacitor, the upper lid is deformed upon this rise ofthe pressure so as to swell out. In response to this deformation of theupper lid, the metallic rivets fixed to the upper lid are lifted in thedirection away from the capacitor element. As a result, the metallicconnection between the other end of each of the metallic rivets and eachof the lead-out lead plates from the capacitor element is cut off andthus, the electric circuit of the electrolytic capacitor is broken.

Therefore, the electrolytic capacitor of the present inventioneliminates such drawbacks of the prior art electrolytic capacitorincluding the metallic casing having the weak spot formed by the thinwall portion of the bottom that misty driving electrolyte spouted out ofthe metallic casing soils interior of the electronic applianceincorporating the prior art electrolytic capacitor and is mistaken forsmoke due to a fire.

Meanwhile, in the present invention, since components provided in a flowpath of electric current from the external connection terminals to thecapacitor element are merely the metallic rivets and the lead-out leadplates, the electrolytic capacitor is structurally simplified.Furthermore, in the present invention, since the number of connectionsin the electrolytic capacitor is reduced substantially in comparisonwith that of a known electrolytic capacitor with an open circuit modemechanism, the electrolytic capacitor is quite useful in terms of thenumber of its assembly steps and reliability of the connections.

In addition, in the present invention, since a weak spot having areduced cross-sectional area as in the case of the known electrolyticcapacitor with the open circuit mode mechanism is not provided in theelectric circuit of the electrolytic capacitor, such a problem of theknown electrolytic capacitor is eliminated that since the weak spothaving the reduced cross-sectional area is heated due to its largeelectric resistance, ripple current (AC) capacity is sacrificed, therebyresulting in great safety of the electrolytic capacitor with the opencircuit mode mechanism.

What is claimed is:
 1. An electrolytic capacitor comprising:a capacitorelement impregnated with electrolyte and having a pair of lead-out leadplates; a cylindrical metallic casing including a bottom, a curled endforming a mouth, and a transverse drawing portion at said mouth, saidcapacitor element being accommodated in said casing; a lid for enclosingsaid mouth of said casing, said lid having a peripheral portion; a pairof metallic rivets secured to and extending through said lid, each ofsaid rivets having a first end and a second end; a pair of externalconnection terminals, each of said terminals being connected to saidfirst end of one of said rivets; a jig for gripping said second end ofeach of said rivets; a fixing member formed of resin and having a pairof through-holes, at least one communication hole for allowingcommunication between said capacitor element and said lid, a peripheralportion positioned on said transverse drawing portion of said casing,and a jig opening for allowing insertion of said jig, said peripheralportion of said lid being positioned on said peripheral portion of saidfixing member, said second end of each of said rivets being positionedin one of said through-holes so as to project from said fixing member ina direction away from said lid, said second end of each of said rivetsbeing metallically joined to one of said lead plates, wherein each ofsaid through-holes has an area smaller than an area of each of said leadplates at a point where each of said rivets is connected to one of saidlead plates; and packing positioned on said peripheral portion of saidlid, wherein said packing, said peripheral portion of said lid, and saidperipheral portion of said fixing member are hermetically secured tosaid casing between said transverse drawing portion of said casing andsaid curled end of said casing.
 2. An electrolytic capacitorcomprising:a capacitor element impregnated with electrolyte and having apair of lead-out lead plates; a cylindrical metallic casing including abottom, a curled end forming a mouth, and a transverse drawing portionat said mouth, said capacitor element being accommodated in said casing;a lid for enclosing said mouth of said casing, said lid having aperipheral portion; a terminal fixing member formed of resin and securedto said lid, said terminal fixing member having a weak portion low inmechanical strength; a pair of metallic rivets integrally held by saidterminal fixing member, each of said rivets having a first end and asecond end; a pair of external connection terminals, each of saidterminals being connected to said first end of one of said rivets; afixing member formed of resin and having a pair of through-holes, atleast one communication hole for allowing communication between saidcapacitor element and said lid, and a peripheral portion positioned onsaid transverse drawing portion of said casing, said peripheral portionof said lid being positioned on said peripheral portion of said fixingmember, said second end of each of said rivets being positioned in oneof said through-holes so as to project from said fixing member in adirection away from said lid, said second end of each of said rivetsbeing metallically joined to one of said lead plates, wherein each ofsaid through-holes has an area smaller than an area of each of said leadplates at a point where each of said rivets is connected to one of saidlead plates; and packing positioned on said peripheral portion of saidlid, wherein said packing, said peripheral portion of said lid, and saidperipheral portion of said fixing member are hermetically secured tosaid casing between said transverse drawing portion of said casing andsaid curled end of said casing.
 3. An electrolytic capacitorcomprising:a capacitor element impregnated with electrolyte and having apair of lead-out lead plates; a cylindrical metallic casing including abottom, a curled end forming a mouth, and a transverse drawing portionat said mouth, said capacitor element being accommodated in said casing;a lid for enclosing said mouth of said casing, said lid having aperipheral portion and a longitudinal plastic elongation portion; aterminal fixing member formed of resin and secured to said lid; a pairof metallic rivets integrally held by said terminal fixing member, eachof said rivets having a first end and a second end a pair of externalconnection terminals, each of said terminals being connected to saidfirst end of one of said rivets; a fixing member formed of resin andhaving a pair of through-holes, at least one communication hole forallowing communication between said capacitor element and said lid, anda peripheral portion positioned on said transverse drawing portion ofsaid casing, said peripheral portion of said lid being positioned onsaid peripheral portion of said fixing member, said second end of eachof said rivets being positioned in one of said through-holes so as toproject from said fixing member in a direction away from said lid, saidsecond end of each of said rivets being metallically joined to one ofsaid lead plates, wherein each of said through-holes has an area smallerthan an area of each of said lead plates at a point where each of saidrivets is connected to one of said lead plates; and packing positionedon said peripheral portion of said lid, wherein said packing, saidperipheral portion of said lid, and said peripheral portion of saidfixing member are hermetically secured to said casing between saidtransverse drawing portion of said casing and said curled end of saidcasing.
 4. An electrolytic capacitor comprising:a capacitor elementimpregnated with electrolyte and having a pair of lead-out lead plates;a metallic casing including a bottom, a curled end forming a mouth, anda transverse drawing portion at said mouth, said capacitor element beingaccommodated in said casing; a lid for enclosing said mouth of saidcasing, said lid having a peripheral portion; a pair of metallic rivetssecured to and extending through said lid, each of said rivets having afirst end and a second end; a pair of external connection terminals,each of said terminals being connected to said first end of one of saidrivets; a fixing member formed of resin and secured to said capacitorelement, said fixing member including a pair of through-holes, at leastone communication hole for allowing communication between said capacitorelement and said lid, and a peripheral portion positioned on saidtransverse drawing portion of said casing, said peripheral portion ofsaid lid being positioned on said peripheral portion of said fixingmember, said second end of each of said rivets being positioned in oneof said through-holes so as to project from said fixing member in adirection away from said lid, said second end of each of said rivetsbeing connected to one of said lead plates, wherein each of saidthrough-holes has an area smaller than an area of each of said leadplates at a point where each of said rivets is connected to one of saidlead plates; and packing positioned on said peripheral portion of saidlid, wherein said packing, said peripheral portion of said lid, and saidperipheral portion of said fixing member are hermetically secured tosaid casing between said transverse drawing portion of said casing andsaid curled end of said casing.
 5. The electrolytic capacitor of claim4, wherein said second end of each of said rivets is metallically joinedto one of said lead plates.
 6. The electrolytic capacitor of claim 5,wherein said second end of each of said rivets is connected to one ofsaid lead plates by one of an ultrasonic welding connection, a laserwelding connection, a cold pressure welding connection, and a crimpingconnection.
 7. The electrolytic capacitor of claim 4, wherein saidsecond end of each of said rivets is connected to one of said leadplates by one of an ultrasonic welding connection, a laser weldingconnection, a cold pressure welding connection, and a crimpingconnection.
 8. The electrolytic capacitor of claim 4, wherein whenpressure in said casing increases, only said peripheral portion of saidlid is deformed such that a distance between said pair of externalconnection terminals is maintained constant.
 9. The electrolyticcapacitor of claim 4, wherein said casing has a cylindrical shape. 10.The electrolytic capacitor of claim 4, wherein said fixing member has alongitudinal projection, said capacitor element having a winding corecavity, said projection extending into said winding core cavity so as tosecure said fixing member to said capacitor element.
 11. Theelectrolytic capacitor of claim 10, wherein said fixing member and saidprojection are formed as a unitary member.
 12. The electrolyticcapacitor of claim 4, wherein said fixing member is unattached to saidlid.